This invention relates to a method for preparing metal organic compounds. More particularly, this invention relates to a method of preparing hydrocarbyl substituted dithiocarbamates of molybdenum. Still more particularly, this invention relates to a method of preparing hydrocarbyl substituted dithiocarbamates of molybdenum containing molybdenum in a VI.sup.+ oxidation state.
Processes for preparing hydrocarbyl substituted dithiocarbamates or molybdenum (VI) have been proposed heretofore. In such processes, a solution of an alkali metal hydrocarbyl substituted dithiocarbamate and an alkali metal molybdate is neutralized with an inorganic acid such as nitric acid, hydrochloric acid, etc., followed by extraction and oxidation with a strong oxidizing agent such as t-butylhydroperoxide. These processes have not, however, been effective for the production of dithiocarbamates of molybdenum (VI) with hydrocarbyl substituted groups containing more than about four carbon atoms. Moreover, the extraction and oxidation steps required by the prior art processes complicate the production of such hydrocarbyl substituted dithiocarbamates. Further, when the hydrocarbyl groups are branched rather than straight chained, di-substituted dithiocarbamates of molybdenum VI could not be prepared and unidentified tars which could not be purified resulted. Still further, in the preparation of dihydrocarbyl substituted dithiocarbamates with these prior art processes, a 50% excess of sodium molybdate has been recommended. These methods, then, are wasteful and do not fully utilize the metal. Finally, these methods of producing such hydrocarbyl substituted dithiocarbamates are indirect and not well suited for large scale preparations.
Recently, it has been learned that certain dihydrocarbyl substituted dithiocarbamates of various metals are particularly effective catalyst precursors in certain hydroconversion processes. This discovery is the subject of co-pending U.S. patent application Ser. No. 608,308 which was filed on May 8, 1984. More recently, it has been discovered that dihydrocarbyl substituted dithiocarbamates of molybdenum (VI) are particularly effective as catalyst precursors in certain of these hydroconversion processes. In light of these discoveries, the need for a process for preparing dihydrocarbyl substituted dithiocarbamates having about four or more carbon atoms in the hydrocarbyl substitution and the need for an improved process for making such dithiocarbamates wherein the hydrocarbyl substitution contains from about 1 to 3 carbon atoms is, then, believed to be readily apparent.